In the field of integrated circuit chips (i.e., system-on-chip devices), sensing the current drawn from electrical power sources is often performed to autonomously manage power consumption of the integrated circuit chips. If too much electrical power is drawn from an electrical power source, the electrical power source can shut down or fail (e.g., become damaged). Furthermore, if too much electrical power is drawn by a chip, the chip can get hot and possibly melt. Also, a customer may want the amount of electrical power that a chip consumes to be limited for reasons of utility costs and environmental concerns.
Traditionally, two approaches have been used to sense the current drawn by an integrated circuit chip. A first method measures the current externally in the power source supplying the chip, and then transfers the current information to the chip via dedicated primary inputs. However, such dedicated primary inputs add cost to the chip. A second method involves building a high precision resistor into the chip between the power source and the load, along with a voltage sensor to measure a voltage drop across the resistor during operation. However, this resistor approach wastes power proportional to the square of the current drawn multiplied by the resistance value chosen.